Eye movement in response to visual stimuli for assessment of ophthalmic and neurological conditions

ABSTRACT

The present invention generally relates to apparatus, software and methods for assessing ocular, ophthalmic, neurological, physiological, psychological and/or behavioral conditions. As disclosed herein, the conditions are assessed using eye-tracking technology that beneficially eliminates the need for a subject to fixate and maintain focus during testing or to produce a secondary (non-optical) physical movement or audible response, i.e., feedback. The subject is only required to look at a series of individual visual stimuli, which is generally an involuntary reaction. The reduced need for cognitive and/or physical involvement of a subject allows the present modalities to achieve greater accuracy, due to reduced human error, and to be used with a wide variety of subjects, including small children, patients with physical disabilities or injuries, patients with diminished mental capacity, elderly patients, animals, etc.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application, filed under 35 U.S.C.§ 371, of International Patent Application No. PCT/US18/63522, filedDec. 1, 2018, which claims the benefit of and priority to U.S.Provisional Patent Application No. 62/708,070, filed Dec. 1, 2017, bothof which are hereby incorporated by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

None.

BACKGROUND

Vision is the primary sense used by humans in daily life, but over 285million people in the world are visually impaired, of whom 39 millionare blind and 246 million have moderate to severe visual impairment. Theleading cause of blindness is cataract, which is readily treatablethrough surgery. Glaucoma is the 2nd leading cause of blindness in theworld. In contrast to cataract, glaucoma is not curable. At best, theprogression of visual field loss due to glaucoma can be stopped ordelayed. Age-related macular degeneration (AMD), the 3rd leading causeof blindness, is generally not curable, and vision loss due to diabeticretinopathy is a developing epidemic. Therefore, there is an urgent needfor the development of early detection methods and the deployment oftimely countermeasures.

In addition to ophthalmic conditions, many neurological conditions canbe diagnosed, assessed, classified, graded and/or treated using visualtracking modalities. With increased attention to threats or adverseeffects to brain health, such as concussions and traumatic braininjuries (TBI) resulting from, e.g., military activities, contact sportsand athletic activities, as well as post traumatic stress disorderresulting from a wide variety of circumstances, new methods for reliablyand objectively identifying injuries and facilitating recovery areneeded.

However, existing visual opthalmic and neurological tests typicallyrequire a subject to fixate for an extended period of time withoutlosing focus and to actively respond to qeues from the test protocolwith physical movements or audible indications, i.e., feedback. Theserequirements limit the accuracy and thereby clinical useability of testresults due to human error and prevent testing of subjects that areincapable of meeting the test criteria (e.g., small children, patientswith physical disabilities or injuries, patients with diminished mentalcapacity, elderly patients, animals, etc.).

US Patent Pub. No. 2017/0290504 discloses the use of gaming applicationswhere visual tracking of multiple objects is used to test users' visionperformance and to create visual profiles for users of virtual,augmented or mixed reality systems. The vision profiles for user groupsbecome available to developers for use in modifying media to betteralign with users' visual characteristics, but the gaming applicationsare not altered ad hoc to probe users' visual deficiencies. Inparticular, US Patent Pub. No. 2017/0290504, for example, does notdisclose an opportunistic testing of users' vision performance based ontheir individual responses throughout the testing.

SUMMARY

The present invention generally relates to apparatus, software andmethods for assessing (e.g., detecting, classifying, grading and/ortreating) ocular, ophthalmic, neurological, physiological, psychologicaland/or behavioral conditions. As disclosed herein, the conditions areassessed using eye-tracking technology that beneficially eliminates theneed for a subject to fixate and maintain focus during testing or toproduce a secondary (non-optical) physical movement or audible response,i.e., feedback. The subject is only required to look at a series ofindividual visual stimuli, which is generally an involuntary reaction.The reduced need for cognitive and/or physical involvement of a subjectallows the present modalities to achieve greater accuracy, due toreduced human error, and to be used with a wide variety of subjects,including small children, patients with physical disabilities orinjuries, patients with diminished mental capacity, elderly patients,animals, etc. Further, the use of opportunistic algorithms in someembodiments of the present apparatus, software and methods allows forthe dense collection of data at locations of a potential problem andsparser collection of data elsewhere, thereby potentially shorteningtesting time while more accurately capturing problem locations, such as,but not limited to, visual field defects or scotomas.

The apparatus, software and methods disclosed herein may also be used toimprove ophthalmic and/or neurological performance. For example, theapparatus, software and methods may be used to gauge and improve (train)reaction time and accuracy to stimuli for an athlete, pilot, astronaut,first responder, military participant (e.g., warfighter), etc. They mayalso be used to gauge and improve (train) reaction time and accuracy tostimuli for persons with neurological (or other) injuries and/ordiseases.

In an aspect, an apparatus for assessing at least one of an ocular,ophthalmic, neurological, physiological, psychological or behavioralcondition comprises a light-emitting device configured for displaying aseries of individual visual stimuli to a subject; at least one sensorfor tracking eye movement of the subject in response to each of theindividual visual stimuli and generating data indicative of the trackedeye movement; and a processor for (i) analyzing the data indicative ofthe tracked eye movement; (ii) instructing the light-emitting device todisplay the individual visual stimuli, wherein at least one stimulus inthe series of individual visual stimuli is placed opportunistically; and(iii) assessing the presence, absence, type and/or extent of the ocular,ophthalmic, neurological, physiological, psychological and/or behavioralcondition.

In an embodiment, an opportunistic placement is based on a subject'sresponse to at least one prior stimulus, a subject's response to onlyone stimulus, a subject's response to only the immediately precedingstimulus, or a subject's response to a plurality of prior stimuli.

In an embodiment, the apparatus further comprises memory for storingdata indicative of the tracked eye movement.

In an embodiment, a processor of the apparatus executes at least one ofa deterministic algorithm, a non-deterministic algorithm, a stochasticalgorithm, a machine learning algorithm, a deep learning algorithm or acombination thereof.

In an embodiment, the apparatus comprises a virtual reality headset, anaugmented reality headset, a mixed reality headset or another devicewith a built-in or auxiliary eye-tracking device.

In an embodiment, a sensor for tracking eye movement of the subject isselected from the group consisting of a camera, an infrared sensor andcombinations thereof.

In an embodiment, a light-emitting device displays visual stimulimonocularly or binocularly to test a subject. Regardless of whether thetesting is monocular or binocular, eye/gaze tracking data may becollected monocularly (for the eye receiving the visual stimuli or forthe eye that is not receiving the visual stimuli) or binocularly (evenif only one eye is receiving the visual stimuli).

In an embodiment, an assessment of at least one of an ocular,ophthalmic, neurological, physiological, psychological or behavioralcondition comprises presenting only one visual stimulus to a subjectwith a light-emitting device; tracking the subject's gaze in response tothe visual stimulus with a sensor configured to acquire eye movementdata; analyzing the data indicative of the tracked eye movement; andassessing the presence, absence, type and/or extent of the ocular,ophthalmic, neurological, physiological, psychological and/or behavioralcondition.

In an embodiment, the light-emitting device may display the visualstimuli as a point of light on a background or an illuminated object orshape, wherein the light, the background, and/or the object or shape areblack, white, colored, opaque, translucent, textured, of variedcontrast, steady or flickering at a predetermined or opportunisticallydetermined frequency, or combinations thereof. In an embodiment, thelight-emitting device displays the visual stimuli on a parallel plane, awarped plane, an irregular plane, a convex surface, a concave surface,or in 3D space. For example, the light-emitting device may comprise aprojector, a light-emitting diode, a light bulb, a fluorescing body, aliquid crystal, an electroluminescent particle, electronic ink, acathode ray tube (CRT), a laser, a carbon nanotube, plasma, a quantumdot and combinations thereof. In an embodiment, the light-emittingdevice displays the visual stimuli on a physical surface/object or agenerated or virtual surface/object. For example, the light-emittingdevice may display the visual stimuli on a display screen, a wall, abuilding, a point cloud, or a physical object.

In an embodiment, a subject is a human or a non-human animal. Forexample, a subject may be a patient, an athlete, a pilot, an astronaut,a driver, a military participant, a civilian, an equipment or machineryoperator, or a first responder. In an embodiment, a subject may be anon-human mammal such as a canine, a feline, a porcine, a bovine, anequine, an ovine, a murine or the like.

In an embodiment, data indicative of eye movement are representative ofthe subject's central vision, the subject's peripheral vision, or both.In other words, apparatus, software and methods of the present inventionare capable of performing campimetry, perimetry or both.

In an embodiment, data indicative of eye movement is spatial data,temporal data or spatiotemporal data. In an embodiment, data indicativeof eye movement comprises gaze coordinates or gaze coordinates as afunction of time. In an embodiment, gaze coordinates are selected fromthe group consisting of polar coordinates, Cartesian coordinates, pixelcoordinates, spherical coordinates, cylindrical coordinates andcombinations thereof.

In an embodiment, analyzing the stored data comprises extracting one ormore observables, correlating one or more gaze coordinates with a fieldof view or combinations thereof. For example, the one or moreobservables may be selected from the group consisting of visualdetection, gaze trajectory, response time, visual acuity, ability tofixate, overshoot/undershoot, saccadic movement, micro-saccadicmovement, field of view, quality of the subject's central vision,quality of the subject's peripheral vision, eye coordination,strabismus, color vision, contrast sensitivity, object perception, shapeperception, texture perception, flicker frequency perception andcombinations thereof.

In an embodiment, an apparatus further comprises an output device forreporting at least one of the tracked eye movement(s) and the presence,absence, type and/or extent of at least one ocular, ophthalmic,neurological, physiological, psychological, or behavioral condition. Inan embodiment, the output device is a graphical interface, a textinterface, a VR (Virtual Reality)/AR (Augmented Reality)/MR (MixedReality) interface, a printer, a text and/or graphical report n physicalor digital form, an audio or video signal output or a set of outputs.

In an embodiment, the ocular, ophthalmic, neurological, physiological,psychological, or behavioral condition is selected from the groupconsisting of retinal defects, optic nerve defects, cortical defects,blindness, color blindness, macular degeneration, concussion, traumaticbrain injury (TBI), brain damage, diabetic retinopathy, glaucoma,cataract, epilepsy, post traumatic stress disorder (PTSD), strabismus,lazy eye tendencies, metamorphopsia, saccades, micro-saccades, influenceof intoxicants, general eye coordination, alertness, sleep apnea andcombinations thereof.

In an aspect, a non-transitory computer-readable medium for assessing atleast one of an ocular, ophthalmic, neurological, physiological,psychological or behavioral condition comprises instructions stored onthe computer-readable medium that when executed on a processor cause theprocessor to: instruct a light-emitting device to display a series ofindividual visual stimuli to a subject, wherein at least one stimulus inthe series of individual visual stimuli is placed opportunistically;acquire data from at least one sensor that tracks eye movement of thesubject in response to each of the individual visual stimuli; analyzethe data indicative of the tracked eye movement; and assess thepresence, absence, type and/or extent of the ocular, ophthalmic,neurological, physiological, psychological and/or behavioral condition.

In an embodiment, the non-transitory computer-readable medium furthercomprises instructions for storing data indicative of the tracked eyemovement to memory. In an embodiment, the non-transitorycomputer-readable medium further comprises instructions for reporting anassessment of the ocular, ophthalmic, neurological, physiological,psychological and/or behavioral condition on an output device.

In an aspect, a method of assessing at least one of an ocular,ophthalmic, neurological, physiological, psychological, or behavioralcondition of a subject using a computing device programmed to execute aplurality of programmatic instructions, comprises: presenting a seriesof individual visual stimuli to a subject with a light-emitting devicecoupled to the computing device, wherein at least one stimulus in theseries of individual visual stimuli is placed opportunistically;tracking the subject's gaze in response to each of the individual visualstimuli with a sensor configured to acquire eye movement data; analyzingthe data indicative of the tracked eye movement; and assessing thepresence, absence, type and/or extent of the ocular, ophthalmic,neurological, physiological, psychological and/or behavioral condition.

In an embodiment, the step of presenting the series of visual stimulicomprises presenting a first stimulus in a first location and presentinga second stimulus in a second location different from the first locationor the same as the first location, e.g. for repeat measurements.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present invention are described indetail below with reference to the attached drawings, wherein:

FIG. 1 is a flowchart illustrating exemplary steps within a virtualopportunistic reaction perimetry (VORP) test protocol;

FIG. 2 is an example of a corrected examination log plot showing acompilation of VORP test data;

FIG. 3 is an example of an individual visual stimulus of FIG. 2 andcorresponding gaze trajectory data in response to that visual stimulus;and

FIG. 4 is a block diagram of an exemplary apparatus for assessing atleast one ocular, ophthalmic, neurological, physiological,psychological, or behavioral condition.

DETAILED DESCRIPTION

In general, the terms and phrases used herein have their art-recognizedmeaning, which can be found by reference to standard texts, journalreferences and contexts known to those skilled in the art. The followingdefinitions are provided to clarify their specific use in the context ofthis description.

As used herein, “virtual reality (VR)” refers to an immersivecomputer-simulated fully artificial digital environment, or thecomputer-generated simulation of a three-dimensional image orenvironment that can be interacted with in a seemingly real or physicalway by a person using special electronic equipment, such as a helmetwith a screen inside and/or gloves fitted with sensors.

As used herein, “augmented reality (AR)” refers to technology thatsuperimposes a computer-generated image on a user's view of the realworld, thus providing a composite view.

As used herein, “mixed reality (MR)” refers to a hybrid reality wherevirtual objects are overlaid upon and anchored to the real world suchthat the user can interact with the virtual objects.

As used herein, “opportunistic” describes something that is dependentupon an earlier result. Therefore, an “opportunistic visual stimulus” or“an opportunistically placed visual stimulus” is dependent upon asubject's response or non-response to at least one prior visualstimulus. For example, a subsequent visual stimulus that isopportunistically placed may be positioned to confirm a prior result ormap the boundaries of an identified weakness or deficiency, e.g., avisual field defect or scotoma.

As used herein, a “series” includes two or more items, and a “series ofindividual visual stimuli” includes two or more visual stimuli that areindividually displayed (i.e., the stimuli in the series are presentedone at a time).

As used herein, the terms “eye movement” and “gaze movement” are usedinterchangeably to refer to a physiological response to a stimulus froma subject's eye(s). In addition, the terms “eye tracking” and “gazetracking” are used interchangeably to refer to sensor output that isrepresentative of the eye/gaze movement. In some embodiments, the sensoroutput is converted into “eye coordinates” or “gaze coordinates”, whichmay be used interchangeably herein.

As used herein, “eccentricity” refers to the location of a light/visualstimulus with respect to a subject's current gaze location.

As used herein, a “deterministic algorithm” is an algorithm which, givena particular input, will always produce the same output, with theunderlying machine always passing through the same sequence of states.

As used herein, a “non-deterministic algorithm” or “stochasticalgorithm” or “probabilistic algorithm” is an algorithm which, given aparticular input, will in general not produce the same output, with theunderlying machine in general not passing through the same sequence ofstates. Such algorithm usually includes an element of randomness.

As used herein, a “machine learning algorithm” refers to an algorithmthat builds or learns a mathematical model based on sample data in orderto make predictions or decisions without being explicitly programmed toperform the task. Machine learning algorithms comprise, but are notlimited to: logistic regression algorithms; decision trees; ensemblemethods; level-set methods; cognitive maps; generalized linear models;and clustering algorithms.

As used herein, “deep learning” refers to a class of machine learningalgorithms that use a cascade of multiple layers of nonlinear processingunits for feature extraction and transformation. Each successive layeruses the output from the previous layer as input. For example, deeplearning algorithms comprise, but are not limited to: feedforwardnetworks, multi-layer perceptrons, convolutional networks, recurrentneural networks, extreme learning machines, long/short term memorynetworks, auto encoders, modular neural networks, Hopfield attractornetworks.

“Proximal” and “distal” refer to the relative positions of two or moreobjects, planes or surfaces. For example, an object that is close inspace to a reference point relative to the position of another object isconsidered proximal to the reference point, whereas an object that isfurther away in space from a reference point relative to the position ofanother object is considered distal to the reference point.

The terms “direct and indirect” describe the actions or physicalpositions of one object relative to another object. For example, anobject that “directly” acts upon or touches another object does sowithout intervention from an intermediary. Contrarily, an object that“indirectly” acts upon or touches another object does so through anintermediary (e.g., a third component).

FIG. 1 is a flowchart 100 illustrating exemplary steps within a virtualopportunistic reaction perimetry (VORP) test protocol carried out, forexample, on a VR, AR or MR head mounted display. In step 102, one fieldof view is turned dark. In other words, the input for one eye that isnot being tested is set to a dark or black background to accomplishmonocular testing of the other eye. This input remains inactive/staticduring testing of the other eye. In step 104, the other field of viewfor the tested eye is set to a user-defined color (usually black). Instep 106, monocular eye/gaze tracking for the eye being tested is turnedON, and stays ON for the entire test and eye/gaze tracking data arerecorded. In a separate instantiation (not shown), gaze tracking forboth eyes may be turned ON and/or gaze tracking may be turned ON onlywhen a visual stimulus is presented. Step 108 is a query to determinewhether all eccentricities or visual stimulus locations have beentested. If the answer to query 108 is yes, the VORP test is finished, asindicated in step 110. If the answer to query 108 is no, a visualstimulus is displayed (step 112) and eye/gaze tracking data associatedwith the subject's response to the visual stimulus are evaluated (step114). The location of a visual stimulus may be selected, for example,according to user-defined specifications and/or an outside controlalgorithm, such as a lookup table or map or an opportunistic algorithm.If a lookup table/map is used, a visual stimulus is placed in a locationwith respect to the current eye/gaze position that most closely matchesthe eccentricities of an untested location on the lookup table/map. Ifan opportunistic control algorithm is used, the visual stimulus isplaced in a location with respect to the current eye/gaze position thatnot only delivers a previously untested eccentricity, but may also zoomin and map out or delineate an area where the subject may have exhibitedatypical behavior, e.g., a visual field defect or scotoma. Note, thatsubsequent visual stimuli locations are dependent upon a subject'scurrent eye/gaze position because the subject may not return his or hergaze to a neutral position after every stimulus event. This ability ofthe present apparatus, software and methods to adapt to currentconditions in real time alleviates the burden on the subject to maintainfocus and remember to return to the neutral position after each visualstimulus is presented, and it improves results by eliminating orreducing human error.

Step 116 is a query to determine whether the subject's gaze position endpoint was sufficiently close to the visual stimulus location. If theanswer to query 116 is yes, the method returns to step 108 to determinewhether all eccentricities/locations have been tested. If the answer toquery 116 is no, meaning that the gaze position end point was notsufficiently close to the visual stimulus location or there was nosubject response to the visual stimulus at all, a second query 118determines whether a scotoma contingency protocol is finished. If theanswer to query 118 is yes, the scotoma contingency protocol is finishedeven though the last gaze position end point was not sufficiently closeto the visual stimulus location (e.g., which may occur when a visualdefect or scotoma is identified and confirmed), and the test continueswith step 108. If the answer to query 118 is no, meaning the scotomacontingency protocol is not finished, a visual stimulus is displayedaccording to the scotoma contingency protocol (step 120) and eyetracking data associated with the subject's response to the visualstimulus are evaluated (step 114). The scotoma contingency protocol may,for example, retest the exact same eccentricity that caused a negativeresponse to query 116 to confirm the result, retest the sameeccentricity that caused the negative response to query 116 with adifferent color, contrast, shape, brightness, texture, flicker frequencyor other characteristic, singularly or in any combination, to determinethe cause of the result, test one or more eccentricities near theeccentricity that caused a negative response to query 116 therebymapping the boundaries of a potential defect (e.g., visual field defector scotoma), or a combination of the above. The notion of the subject'sgaze position end point being sufficiently close to a visual stimuluslocation can be based, e.g., on a distance measure, such as, but notlimited to the Euclidean distance between the subject's gaze positionend point and the visual stimulus location, or on an angle measure, suchas the visual field angle between the subject's gaze position end pointand the visual stimulus location. In some embodiments, sufficientlyclose end points are less than or equal to 3 degrees of visual fieldfrom the visual stimulus location, or less than or equal to 2 degrees ofvisual field from the visual stimulus location, or less than or equal to1 degree of visual field from the visual stimulus location, or less thanor equal to 0.5 degree of visual field from the visual stimuluslocation. In an embodiment, a sufficiently close end point may bedefined by a Euclidean distance within any of the immediately precedingranges.

Flowchart 100 illustrates exemplary steps, which may be modified fordifferent test purposes. For example, step 116 may include additional oralternative queries, such as did the subject overshoot/undershoot thevisual stimulus location? Was the response time under or over aparticular threshold? Has the visual stimulus location been tested apredetermined number of times? Was the eye/gaze trajectory sufficientlylinear?

FIG. 2 is an example of a corrected examination log (i.e., log of theexamination) plot showing a compilation of VORP test data. The plot arearepresents the visual field of a subject with the horizontal range onthe x-axis and the vertical range on the y-axis. “X” marks indicate thepositions of the visual stimuli presented to the subject over the courseof the test. The visual stimuli were presented to the subjectindividually (i.e., one at a time) with the prior stimulus removedbefore a subsequent stimulus was presented. The lines show the subject'sgaze trajectory toward each stimulus in response to that stimulus.

FIG. 3 is an example of an individual visual stimulus of FIG. 2 andcorresponding gaze trajectory data in response to that visual stimulus.

FIG. 4 is a block diagram of an exemplary apparatus 400 for assessing atleast one ocular, ophthalmic, neurological, physiological,psychological, or behavioral condition. Apparatus 400 comprises alight-emitting device 402 configured for displaying a series ofindividual visual stimuli, represented by arrow 404, to a subject. Atleast one sensor 406 tracks eye/gaze movement of the subject in responseto each of the individual visual stimuli and generates data indicativeof the tracked eye/gaze movement. The data are sent to bus 408, and thento storage (not shown) or to a processor 410. Processor 410 instructslight-emitting device 402 to display/opportunistically place visualstimuli, analyzes data indicative of the tracked eye/gaze movement byexecuting software 412 stored in memory 414, and ultimately, assessesthe presence, absence, type and/or extent of the ocular, ophthalmic,neurological, physiological, psychological and/or behavioral condition.In an embodiment, the information generated in the assessment step maybe reported on an output device 416.

Although FIG. 4 illustrates one apparatus 400, structures andfunctionality presented as a single component may be implemented asseparate components. For example, processor 410, memory 414 and software412 may reside within an external computer that communicates with aVR/AR/MR headset through an input/output device 416. The VR/AR/MRheadset may include light-emitting device 402 and sensor 406. Further, asingle component, such as apparatus 400, may include multiple structuresrepresented by a single block, e.g., multiple processors 410,light-emitting devices 402 and sensors 406, may be present in apparatus400.

The one or more processors may also operate to support performance ofthe relevant functionality in a “cloud computing” environment or as a“software as a service” (SaaS). For example, at least some of thefunctions may be performed by a group of computers accessible via anetwork (e.g., the Internet) and via one or more appropriate interfaces(e.g., application program interfaces (APIs).

The apparatus, software and methods disclosed herein are furtherillustrated by the following Example. This Example is for illustrativepurposes only and is not intended to limit the invention.

EXAMPLE

This Example illustrates a virtual opportunistic reaction perimetry(VORP) test using a virtual reality head mounted display (VR HMD).

Equipment

A VR HMD (head mounted display) or equivalent with usually two videofeeds, i.e., one for the left eye and one for the right eye, is used.The VR HMD is equipped with real-time eye tracking (preferably 60 Hz ormore) for the left and right eye, respectively. For example, usefulspecifications are: infrared eye tracking system×2, tracking accuracy ofless than 1 degree, frame rate of 120 fps.

DESCRIPTION

To test the central and peripheral vision of subjects, i.e., perimetrybased on campimetry, point-like light stimuli are presented as a seriesof individual stimuli. As opposed to standard automated perimetry (e.g.,using a Zeiss Humphrey Visual Field Analyzer), the subject is NOTrequired to maintain fixation throughout the entire test exam, nor isthe subject required to push a button or provide verbal feedback toacknowledge the perception of a light stimulus.

Overview of VORP Procedure

The video feed for the eye not being tested is turned off or moved to ablack or dark state. For the eye being tested, the eye tracking sensorconstantly reports the current eye/gaze location. The subject is askedto “chase” perceived light stimuli that are being presented atpseudo-random locations within the field of view of the VR HMD andsubject. In other words, given any current eye/gaze location, thegoverning test program (i.e., code) can calculate the location of alight stimulus for subsequent presentation within the available realestate of the VR HMD (i.e., the video feed for that eye) for aneccentricity/location that has not been covered at all or notsufficiently covered yet in the current test session. If the subjectsees the stimulus and moves his eye/gaze to the location of that laststimulus, the governing test program can exploit this toopportunistically present a stimulus at a farther, same, or closerdistance/eccentricity from the eye's current location. For example, ifthe subject focuses on the center of the VR HMD hemi-screen, and thehorizontal dimension of the screen is 20 degrees to either side fromcenter of fixation, a light stimulus presented at either 20 degreelocation would “force” the eye/gaze to go there. Once there, a lightstimulus can be presented at the opposite end of the VR HMD hemi-screen,to now yield a 40 degree eccentricity location and visual field testing.That way, over time, a meaningful visual field can be tested. Theoverall time of the testing procedure is not fixed, and depends on howquickly the governing test program completes a sufficient visual fieldscreening directly dependent on the eye/gaze movement, i.e., theresponse of the subject.

Detailed VORP Procedure

(1) In an instantiation, generate a rectangular or concentric list/mapof eccentricities to be tested. In the case of VORP, e.g., planar polarcoordinates, i.e., radius and angle, are an ideal choice.

(2) This list/map can be user-defined or computer-generated or randomlygenerated or opportunistically generated in a dynamic fashion (i.e., inreal time during the test).

(3) If the map/list is user-defined it can be interactively generated,uploaded via an external file, or communicated through another computermodule, or any other means for computer system communication known inthe art. Initially a simple configuration file can be used. Eventually,however, the map/list could be dynamically generated and communicatedthrough another computer module that sits on board the VR HMD. Forstarters, this module would be a simple configuration file.

(4) A VR headset with binocular eye-tracking sensors is generally usedbecause it allows for a determination of strabismus, eye-coordination,saccades and micro-saccades.

(5) Monocular testing is recommended, i.e., the eye not being testedshould look at a black or dark screen during the entire time the othereye is being tested.

(6) The patient should ideally be dark adapted. Dark adaption could beaccomplished, e.g., with the VR HMD or in a darkened room prior totesting.

(7) The patient is allowed to “look around” within the test space, i.e.,he does not have to maintain any particular fixation.

(8) Further the patient is asked to “chase” any light stimuli he mightsee by trying to focus his eye/gaze on the stimuli. The light stimulus,in an instantiation, would be a point of light that appears in a fixedposition. In other instantiations, it could be a constantly presentpoint of light that is moving, but this would constitute a differentpsychophysical test modality (i.e., object tracking).

(9) Then the VORP testing procedure commences as follows: depending onwhere the patient eye focus is currently with respect to the boundariesof the tested area in the VR headset, one of the eccentricities (orclosest approximation thereof) of the generated list/map that is (a)feasible with respect to the test area boundaries and (b) not yet testedfor, is stimulated with a light stimulus of fixed, predefined orvariable size, brightness, color, texture, and shape for a certainfixed, predefined or variable time. In addition, the stimulus may have acertain fixed, predefined or variable flicker frequency, or it couldalternate between two or more colors and/or textures. VORP is anopportunistic testing procedure, meaning that wherever the current eyefocus is NOT, is the preferred area to place the next light stimulus tosee whether the patient can notice that light stimulus at thateccentricity with respect to where his current focus is. In addition,repeat testing of prior tested eccentricities and/or locations can occurwith VORP in order to map out the boundaries and/or extents of defects,e.g., visual field defects or scotomas.

With smart and/or opportunistic placement of light stimuli, VORP iscapable of checking most eccentricities on the predefined list/map, or,in addition or alternatively, to test predominantly in areas where thepatient has missed previous light stimuli so as to map out the location,shape and extent of potential scotomas (i.e., visual field defects).

(10) The reaction of the patient's eye with respect to a light stimulusis monitored. Stimulus parameters that may be specified in VORP include,but are not limited to, stimulus size/diameter, stimulus brightness,stimulus color, stimulus contrast, stimulus duration, stimulus texture(Gabor filters), stimulus shape, stimulus flicker frequency,presentation speed of light stimuli, i.e., the time between twoconsecutive light stimuli, hold time of light stimulus, i.e., how long alight stimulus is presented (ON-time) or combinations thereof.

Stimulus size and brightness may help determine the threshold ofcontrast sensitivity of the retina at the particular location of thelight stimulus. Stimulus color may help determine if the patient is moresensitive to certain colors than to others (e.g., green), and/or whetherthe patient suffers from a particular color blindness. Stimulus durationmay help determine overall alertness of the patient (e.g., determiningfatigue in sleep apnea patients, equipment or machinery operators,employees working extended shifts) and reaction speed of the patient(e.g., especially in the elderly). This may be used, e.g., by motorvehicle license issuers to determine the fitness of a subject foroperating a vehicle (subsurface vehicle, surface vehicle, aerial vehicleor space vehicle) or machinery, or by safety regulators to determinewhen an employee is too fatigued to continue working. Stimulus texturemay be used to determine particular deficiencies, e.g., deficienciesrelated to P-cells and/or M-cells. Stimulus shape may help identifymetamorphopsia, e.g., distortions in the visual field.

The stimulus parameters/characteristics described herein could besupplied by an external configuration or initialization file to beloaded into a VORP apparatus, interactively chosen by the user/operatorduring VORP test setup, opportunistically chosen by the VORP programthroughout the test, or communicated through another computer module, orany other means for computer system communication known in the art. Foreach exam the chosen stimulus characteristics/parameters used throughoutthe testing are documented and reported.

The background color may be changed, e.g., to enable a bright yellowbackground with large blue stimuli to emulate blue-yellow perimetry,also known as short wave automated perimetry (SWAP), for earlierGlaucoma detection.

At least the following observables may be recorded via eye/gaze trackingduring the VORP testing procedure: tested eccentricity,direction/path/trajectory of gaze change, velocity of gaze change,overall reaction speed or alertness of a subject, achieved accuracy offocusing on the stimulus if at all, overshooting/undershooting thestimulus location, or meandering around the stimulus location. Thedirection, path, trajectory and velocity of gaze change may beindicative of brain damage, concussions, and traumatic brain injury(TBI).

(11) Points 9 and 10 continue until the entire generated list/map ofeccentricities has been tested.

(12) Retesting of eccentricities can be performed to avoid/reduce falsepositives and false negatives, and/or for statistical purposes.Retesting of eccentricities can also be performed to further map outand/or delineate defects, e.g., visual field defects or scotomas.

(13) The choice of eccentricities from the generated list/map can beopportunistic, random within the confines of feasibility, or following acontrolled protocol. An example of opportunistic eccentricity generationmight include more targeted stimulus generation in areas of the visualfield were an initial defect is detected early on in the test procedure.With smart/opportunistic placement of light stimuli, VORP is capable ofchecking most eccentricities on the predefined list/map, or, in additionor alternatively, of testing predominantly in areas where the subjecthas missed previous light stimuli so as to map out the location, shapeand extent of potential scotomas (i.e., visual field defects).

(14) The possibility that a subject cannot see an eccentricity oreccentricities or all eccentricities (e.g., blind, color-blind, or toodim or small or fast of stimuli) is also taken into account andprogrammatically captured.

(15) Because this is opportunistic reaction perimetry, the overalltesting time per eye may vary. For example, the VORP test time maydepend on how quickly VORP completes a visual field screening given thesubject's eye movement during the test in response to the presentedvisual stimuli. As such an overall maximum cutoff time for the test maybe introduced.

Ocular, ophthalmic, neurological, physiological, psychological orbehavioral conditions that may be tested for by VORP include but are notlimited to: visual field testing (retinal testing, optic nerve testing,and cortical testing), TBI or other brain damage, concussions, earlyonset of AMD or diabetic retinopathy, early onset of glaucoma andcataract, epilepsy, strabismus, lazy-eye determination/assessment,metamorphopsia, general eye coordination, how quickly (i.e., speed) doesthe subject focus on any presented light stimulus (potential insightinto TBI, PTSD, potential glaucoma, etc.), alertness, sleep apnea, howcoordinated does the subject move his eye towards any presented lightstimulus (potential insight into TBI, PTSD, potential glaucoma, etc.),ability to detect multiple defects in a single test (visual fielddefects and color blindness), visual field defects and reaction speed,saccades and micro-saccades, i.e., eye movement, ability to focus on ortrack light stimuli, which may be an indication of being under theinfluence of, e.g., legal or illegal drugs, intoxicants, biohazards(e.g., bacteria and viruses), biological substances, chemicalsubstances, biochemical substances or radiation.

Statements Regarding Incorporation by Reference and Variations

All references cited throughout this application, for example patentdocuments including issued or granted patents or equivalents; patentapplication publications; and non-patent literature documents or othersource material; are hereby incorporated by reference herein in theirentireties, as though individually incorporated by reference, to theextent each reference is at least partially not inconsistent with thedisclosure in this application (for example, a reference that ispartially inconsistent is incorporated by reference except for thepartially inconsistent portion of the reference).

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention inthe use of such terms and expressions of excluding any equivalents ofthe features shown and described or portions thereof, but it isrecognized that various modifications are possible within the scope ofthe invention claimed. Thus, it should be understood that although theinvention has been specifically disclosed by preferred embodiments,exemplary embodiments and optional features, modification and variationof the concepts herein disclosed can be resorted to by those skilled inthe art, and that such modifications and variations are considered to bewithin the scope of this invention as defined by the appended claims.The specific embodiments provided herein are examples of usefulembodiments of the invention and it will be apparent to one skilled inthe art that the invention can be carried out using a large number ofvariations of the devices, device components, and method steps set forthin the present description. As will be apparent to one of skill in theart, methods, software and apparatus/devices can include a large numberof optional elements and steps. All art-known functional equivalents ofmaterials and methods are intended to be included in this disclosure.Nothing herein is to be construed as an admission that the invention isnot entitled to antedate such disclosure by virtue of prior invention.

When a group of substituents is disclosed herein, it is understood thatall individual members of that group and all subgroups are disclosedseparately. When a Markush group or other grouping is used herein, allindividual members of the group and all combinations and subcombinationspossible of the group are intended to be individually included in thedisclosure.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural reference unless thecontext clearly dictates otherwise. Thus, for example, reference to “aprocessor” includes a plurality of such processors and equivalentsthereof known to those skilled in the art, and so forth. As well, theterms “a” (or “an”), “one or more” and “at least one” can be usedinterchangeably herein. It is also to be noted that the terms“comprising”, “including”, and “having” can be used interchangeably. Theexpression “of any of claims XX-YY” (wherein XX and YY refer to claimnumbers) is intended to provide a multiple dependent claim in thealternative form, and in some embodiments is interchangeable with theexpression “as in any one of claims XX-YY.”

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are described.

Whenever a range is given in the specification, for example, a range ofintegers, a temperature range, a time range, a composition range, orconcentration range, all intermediate ranges and subranges, as well asall individual values included in the ranges given are intended to beincluded in the disclosure. As used herein, ranges specifically includethe values provided as endpoint values of the range. As used herein,ranges specifically include all the integer values of the range. Forexample, a range of 1 to 100 specifically includes the end point valuesof 1 and 100. It will be understood that any subranges or individualvalues in a range or subrange that are included in the descriptionherein can be excluded from the claims herein.

As used herein, “comprising” is synonymous and can be usedinterchangeably with “including,” “containing,” or “characterized by,”and is inclusive or open-ended and does not exclude additional,unrecited elements or method steps. As used herein, “consisting of”excludes any element, step, or ingredient not specified in the claimelement. As used herein, “consisting essentially of” does not excludematerials or steps that do not materially affect the basic and novelcharacteristics of the claim. In each instance herein any of the terms“comprising”, “consisting essentially of” and “consisting of” can bereplaced with either of the other two terms. The inventionillustratively described herein suitably can be practiced in the absenceof any element or elements, limitation or limitations which is/are notspecifically disclosed herein.

What is claimed is:
 1. A non-transitory computer-readable medium forassessing at least one of an ocular, ophthalmic, neurological,physiological, psychological or behavioral condition comprisinginstructions stored on the computer-readable medium that when executedon a processor cause the processor to: instruct a light-emitting deviceto display a series of individual visual stimuli to a subject, whereinat least one stimulus in the series of individual visual stimuli isplaced opportunistically; acquire data from at least one sensor thattracks eye movement of the subject in response to each of the individualvisual stimuli; analyze the data indicative of the tracked eye movement;and assess the presence, absence, type and/or extent of the ocular,ophthalmic, neurological, physiological, psychological and/or behavioralcondition.
 2. The non-transitory computer-readable medium of claim 1,wherein the opportunistic placement is based on the subject's responseto at least one prior stimulus, the subject's response to only onestimulus, the subject's response to only the immediately precedingstimulus, or the subject's response to a plurality of prior stimuli. 3.The non-transitory computer-readable medium of claim 1, wherein theinstructions cause the processor to execute at least one of adeterministic algorithm, a non-deterministic algorithm, a stochasticalgorithm, a machine learning algorithm, a deep learning algorithm or acombination thereof.
 4. The non-transitory computer-readable medium ofclaim 1, wherein the light-emitting device displays the visual stimulion a parallel plane, a warped plane, an irregular plane, a convexsurface, a concave surface, or in 3D space.
 5. The non-transitorycomputer-readable medium of claim 1, wherein the light-emitting devicedisplays the visual stimuli on a physical surface or a generatedsurface.
 6. The non-transitory computer-readable medium of claim 1,wherein the data indicative of eye movement comprises gaze coordinatesor gaze coordinates as a function of time.
 7. The non-transitorycomputer-readable medium of claim 1, wherein analyzing the dataindicative of eye movement comprises extracting one or more observablesselected from the group consisting of visual detection, gaze trajectory,response time, visual acuity, ability to fixate, overshoot/undershoot,saccadic movement, micro-saccadic movement, field of view, quality ofthe subject's central vision, quality of the subject's peripheralvision, eye coordination, strabismus, color vision, contrastsensitivity, object perception, shape perception, texture perception,flicker frequency perception and combinations thereof.
 8. Thenon-transitory computer-readable medium of claim 1, wherein thecondition is selected from the group consisting of retinal defects,optic nerve defects, cortical defects, blindness, color blindness,macular degeneration, concussion, traumatic brain injury (TBI), braindamage, diabetic retinopathy, glaucoma, cataract, epilepsy, posttraumatic stress disorder (PTSD), strabismus, lazy eye tendencies,metamorphopsia, saccades, micro-saccades, influence of intoxicants,legal/illegal drugs, biohazards, biological substances, chemicalsubstances, biochemical substances or radiation, general eyecoordination, alertness, sleep apnea and combinations thereof.
 9. Amethod of assessing at least one of an ocular, ophthalmic, neurological,physiological, psychological or behavioral condition of a subject usinga computing device programmed to execute a plurality of programmaticinstructions, comprising: presenting a series of individual visualstimuli to a subject with a light-emitting device coupled to thecomputing device, wherein at least one stimulus in the series ofindividual visual stimuli is placed opportunistically; tracking thesubject's gaze in response to each of the individual visual stimuli witha sensor configured to acquire eye movement data; analyzing the dataindicative of the tracked eye movement; and assessing the presence,absence, type and/or extent of the ocular, ophthalmic, neurological,physiological, psychological and/or behavioral condition.
 10. The methodof claim 9, wherein the opportunistic placement is based on thesubject's response to at least one prior stimulus, the subject'sresponse to only one stimulus, the subject's response to only theimmediately preceding stimulus, or the subject's response to a pluralityof prior stimuli.
 11. The method of claim 9, wherein presenting theseries of individual visual stimuli comprises presenting a firststimulus in a first location and presenting a second stimulus in asecond location different from the first location or the same as thefirst location.
 12. The method of claim 9, wherein the processorexecutes at least one of a deterministic algorithm, a non-deterministicalgorithm, a stochastic algorithm, a machine learning algorithm, a deeplearning algorithm or a combination thereof.
 13. The method of claim 9,wherein the light-emitting device displays the visual stimuli on aparallel plane, a warped plane, an irregular plane, a convex surface, aconcave surface, or in 3D space.
 14. The method of claim 9, wherein thelight-emitting device displays the visual stimuli on a physical surfaceor a generated surface.
 15. The method of claim 9, wherein the dataindicative of eye movement comprises gaze coordinates or gazecoordinates as a function of time.
 16. The method of claim 9, whereinanalyzing the data indicative of eye movement comprises extracting oneor more observables selected from the group consisting of visualdetection, gaze trajectory, response time, visual acuity, ability tofixate, overshoot/undershoot, saccadic movement, micro-saccadicmovement, field of view, quality of the subject's central vision,quality of the subject's peripheral vision, eye coordination,strabismus, color vision, contrast sensitivity, object perception, shapeperception, texture perception, flicker frequency perception andcombinations thereof.
 17. The method of claim 9, wherein the conditionis selected from the group consisting of retinal defects, optic nervedefects, cortical defects, blindness, color blindness, maculardegeneration, concussion, traumatic brain injury (TBI), brain damage,diabetic retinopathy, glaucoma, cataract, epilepsy, post traumaticstress disorder (PTSD), strabismus, lazy eye tendencies, metamorphopsia,saccades, micro-saccades, influence of intoxicants, legal/illegal drugs,biohazards, biological substances, chemical substances, biochemicalsubstances or radiation, general eye coordination, alertness, sleepapnea and combinations thereof.
 18. An apparatus for assessing at leastone of an ocular, ophthalmic, neurological, physiological, psychologicalor behavioral condition comprising: a light-emitting device configuredfor displaying a series of individual visual stimuli to a subject; atleast one sensor for tracking eye movement of the subject in response toeach of the individual visual stimuli and generating data indicative ofthe tracked eye movement; and a processor for (i) analyzing the dataindicative of the tracked eye movement; (ii) instructing thelight-emitting device to display the individual visual stimuli, whereinat least one stimulus in the series of individual visual stimuli isplaced opportunistically; and (iii) assessing the presence, absence,type and/or extent of the ocular, ophthalmic, neurological,physiological, psychological and/or behavioral condition.
 19. Theapparatus of claim 18, wherein the opportunistic placement is based onthe subject's response to at least one prior stimulus, the subject'sresponse to only one stimulus, the subject's response to only theimmediately preceding stimulus, or the subject's response to a pluralityof prior stimuli.
 20. The apparatus of claim 18, wherein the apparatuscomprises a virtual reality headset, an augmented reality headset or amixed reality headset.